Near Normal Rainfall for September for Antigua, Droughts Eased Slightly

29 10 2018

Dale C. S. Destin |

SevereToSeriousThe rainfall for September was near normal for the second month in a row. The total of 107.2 mm (4.22 in) makes September the wettest month for the year, thus far; however, no month has yet had more than near normal. Notwithstanding, the consecutive months of near normal rainfall has led to the droughts easing slightly.

The total rainfall for the month – 107.2 mm was 74% of what normally falls – 144.0 mm (5.67 in). This was not very helpful, given the severe rainfall deficit we are experiencing.

The last three-month period – July to September, upon which the assessment of the current intensity of the drought is based, was seriously dry. In the last three months, only 249.7 mm (9.83 in) of rain fell. This is the 12th driest such period on record dating back to 1928.

Sep2018

Cumulatively, July, August and September normally yield 358.1 mm (14.1 in) of rain; however, a huge 30% of it did not fall. This means that we remain in a severe meteorological drought, the worst category on our drought scale.

So, overall, we remain in a severe drought that is currently at serious intensity. There has been a slight ease from last month – but nothing to shout about.  Recall that the overall description of the drought is based on the worst intensity achieve during its lifetime; however, over time, the intensity will fluctuate.

Potworks Dam, Sep 29, 2018. Courtesy Veronica Yearwood - APUA

Potworks Dam, Sep 29, 2018. Courtesy Veronica Yearwood – APUA

Potworks Dam, with a billion-gallon capacity, has been totally dry for a few months now; however, it got in some water toward the end of August. Notwithstanding, the water levels remains well below extraction level and I am advised that the same is true for the other smaller catchments. These are indicative of the fact that the droughts are at very impactful levels.

The full brunt of the droughts continues to be masked by the presence of the desalination plants, which are virtually still the only source for potable water in the country. Notwithstanding, many impacts are starting to break through. Potable water is still being rationed; places have been left without water for days to weeks, at a time, especially when the sea is stirred up by swells, which negatively impacts the desalination process.

The twelve-month period – October 2017 to September 2018, the duration of the drought thus far, is deemed severely dry. The total for the last eleven months of 714.2 mm (28.12 in) is the third lowest on record and the lowest since 2001. The period normally gets 1202.2 mm (47.33 in) – a little less than twice the amount that fell.

Accumulation_Sep2018

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging. Overall, below normal rainfall is likely for the next six months – November 2018 to April 2019. Thus, there is every reason to believe that the droughts will continue and likely worsen. The chance of the droughts ending is, at most 30% or low.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Nov 2018 - Jan 2019

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Nov 2018 – Jan 2019

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. Will this one go for another four months? Very likely, given the climate signals.

I now expected 2018 to be a drier than normal year with a confidence level of 80%. The best forecast for the amount of rainfall for the year is 845 mm (33.3 in) with a 70% chance of the amount ranging between 623 mm (24.5 in) and 1118 mm (44.0 in). Normally, we get 1206.5 mm (47.5 in) annually,

Keep following us for more on this developing story and all things weather and climate. If you find this article useful, please share it with your family and friends.





Climate Change Played No Part in the 2013-2016 Antigua Drought

17 10 2018

Dale C. S. Destin |

A recently published paper by Herrera et al. has shown that climate change was not a factor in the 2013-2016 Antigua Drought.

The 2013-2016 drought was the worst for Antigua on record, dating back to 1928. Further, the year 2015 was the driest on record dating back to, at least, 1871 or over 145 years. It was a year without a wet season.

DroughtsOfAtLeastOneYear_Thru2016

Water was a huge problem during 2013-2016, many households were without pipe-borne water for days, weeks and even multiple months at a time. The drought was not only meteorological but socioeconomic – the worst kind of drought. The drought is believed to have contributed to the downfall of the then government.

The drought was not limited to Antigua – it was felt all across the region and was deemed one of the worst Pan-Caribbean droughts ever.

The paper by Herrera et al. answered the million question that was raised by many back then – did climate change cause or play a part in our worst drought on record. Some, without a scintilla of evidence, did answer the question in the affirmative. But clearly, science is not what you believe, but what you can prove. And the researchers were able to definitively answer the question, with proof, that climate change neither caused or contributed to the drought.

The Herrera et al. paper titled, Exacerbation of the 2013-2016 Pan-Caribbean Drought by Anthropogenic Warning, showed that not only did climate change not play a part in the Antigua drought – it did not impact the drought across the rest of the Eastern Caribbean. Further, the vast majority of the rest of the drought across the Caribbean was not affected by climate change. The exception is Cuba and to a much lesser extent small parts of Jamaica, Hispaniola and Puerto Rico.

 

Climate Change Contribution (%) to the Drought Severity Across the Caribbean. Hatching (Black Lines) Corresponds to Those Areas Which had a Climate Change Contribution.

Climate Change Contribution (%) to the Drought Severity Across the Caribbean. Hatchings (Black Marks) Highlight Those Areas Which had a Climate Change Contribution.

Notwithstanding the above findings, interestingly, when the Caribbean is viewed as a whole, the authors of the paper found that climate change played a 15 to 17% role in the severity of the Pan-Caribbean drought, forced, of course, mainly by Cuba.

Climate change contributed to the severity of the drought in Cuba was 32%. Without Cuba being a part of this study, the conclusion for the Caribbean, taken as a whole, would be the opposite – climate change played no role in the 2013-2016 drought.

The take-away from the paper is that while climate change had an impact on the drought in Cuba and very small parts of the rest of the Greater Antilles, the rest of the Caribbean cannot credit any part of the drought on climate change.

Although climate change had no part in the drought of 2013-2016 across much of the Caribbean, this is not to say that future drought will not be impacted. The long-term forecast by the Intergovernmental Panel on Climate Change (IPCC) out to the 2100 is for the region to get warmer and drier.

The overall forecast is for climate change to likely cause an increase in the severity and or duration of drought on a regional to global scale. The new report issued by the IPCC on October 8, 2018 offers no update to this position.

Herrera et al. findings strongly suggest that climate model projected climate change drying in the Caribbean is already underway in the larger islands. This has major implications for the many millions of people in those islands and eventually the rest of us in the smaller islands.

Climate change did not affect the drought in Antigua, but it did affect our regional neighbours – the Greater Antilles. It stands to reason that it is only a matter of time before climate change contributes to increasing the severity of droughts elsewhere in the region, including our island.





Near Normal Rainfall for August for Antigua, Droughts Continue

11 10 2018

Dale C. S. Destin |

After seeming on track to becoming the driest August on record in Antigua, an 11th hour spurt of rainfall changed the outcome dramatically and happily. The month ended up with near normal rainfall – 102.9 mm (4.05 in). About 70% of the total occurred on August 29 and 30.

Drought Graphic

August is now the wettest month for 2018 – wetter than the past three months, May to July, combined. This has only every happened 5 other times on record dating back to 1928.

The total rainfall for the month – 102.9 mm was a healthy 91% of what normally falls – 113.0 mm (4.45 in). However, was very far from enough, given the severe rainfall deficit we are experiencing.

The last three-month period – June to August, upon which the assessment of the current intensity of the drought is based, was severely dry. In the last three months, only 155.2 mm (6.11 in) of rain fell. This is the fifth driest such period on record and the second driest since 1986.

Cumulatively, June, July and August normally yield 282.4 mm (11.12 in) of rain; however, a massive 45% of it did not fall. This means that we remain in a severe meteorological drought, the worst category on our drought scale.

Severe_to_SevereSo, overall, we remain in a severe drought that is currently at severe intensity. Last month, it was assessed similarly.  Recall that the overall description of the drought is based on the worst intensity achieve since it started; however, over time, the intensity will fluctuate.

Potworks Dam, with a billion-gallon capacity, has been totally dry for a few months now; however, it got in some water toward the end of August. Notwithstanding, the water levels remains well below extraction level and I am advised by an official of Antigua Public Utilites Authority (APUA) Water Business Unity that the same is true for the other smaller catchments. These are indicative of the fact that the droughts are at severe levels. Nevertheless, the rainfall at the end of August was very useful in tapping up many household cisterns that were or near empty .

Potworks Dam, August 31, 2018, Courtesy Karen Corbin - Humane Society

Potworks Dam, August 31, 2018, Courtesy Karen Corbin – Humane Society.

The full brunt of the droughts continues to be masked by the presence of the desalination plants, which are virtually still the only source for potable water in the country, from the water authority. Notwithstanding, many impacts are starting to break through. Potable water is still being rationed; places have been left without water for days to weeks, at a time, notwithstanding a schedule issued by APUA – the water authority, to provide water to everyone, at least, three times per week.

The eleven-month period – October 2017 to August 2018, the duration of the drought thus far, is deemed severely dry. The total for the last eleven months of 607.1 mm (23.90 in) is the third lowest on record and the lowest since 2001. The period normally gets 1058.2 mm (41.66 in) – a little less than twice the amount that fell.

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging. Overall, below normal rainfall is likely for the next six months – October 2018 to March 2019. Thus, there is every reason to believe that the droughts will continue and likely worsen. The chance of the droughts ending is, at most 30% or low.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Oct-Dec 2018

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Oct-Dec 2018

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. Will this one go for another five months? Very likely, given the climate signals.

Our chance of 2018 being a drier than normal year remains high – 75%, and unchanged from last month. The best forecast for the amount of rainfall for the year is 868 mm (34.2 in) with a 70% chance of the amount ranging between 644 mm (25.4 in) and 1139 mm (44.8 in). Normally, we get 1206.5 mm (47.5 in) annually,

Keep following us for more on this developing story and all things weather and climate. If your find this article useful, please share it with your family and friends.








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